I had a Condor built for me in 1980. Overall, the frame looks very similar, the lugwork and the brake cable braze ons all match. My frame has a head tube decal.
One thing that doesn't match is the bottom bracket. Where the chainstays meet the bottom bracket on your frame doesn't match the rest of the frame (or mine). Also, Monty used a simple straight tube as a reinforcement behind my bottom bracket; yours is more ornate, yet it doesn't look like an ornate frame overall.
Hope that helps!
One thing that doesn't match is the bottom bracket. Where the chainstays meet the bottom bracket on your frame doesn't match the rest of the frame (or mine). Also, Monty used a simple straight tube as a reinforcement behind my bottom bracket; yours is more ornate, yet it doesn't look like an ornate frame overall.
Hope that helps!